1. Field of the Invention
The present invention relates to a camera provided with a magnetic recording function for recording photographic information on a magnetic track provided in correspondence to each frame of film.
2. Description of the Related Art
In recent years cameras have been developed with the capability of magnetically recording data on film. The film used in such cameras has a magnetic track at a position corresponding to each frame (each frame for photographic exposure) of the film. Photographic information is recorded in this magnetic track. This photographic information includes: calendar information of date and time; information of aperture; shutter speed; and other related information. This photographic information is information determined when a photograph of one frame of interest is taken, and the photographic information for each frame is recorded in a magnetic track corresponding to that frame.
The bulletin of Japanese Patent Application Laid Open No. 6-332065 describes a photosensor arranged to detect passage of first and second perforations provided at the winding and rewinding ends so as to be attendant on each frame of film. A time difference is measured between passage start timing of a second perforation attendant on a frame located one frame next to a recording target frame in the winding direction upon winding of film and passage start timing of a first perforation attendant on the recording target frame, detected by the photosensor. A recording frequency of photographic information onto the magnetic track corresponding to the recording target frame is then determined from the time difference thus measured.
However, in cameras arranged to perform winding by electric power, operations carried out in connection with photography include performing the operation of exposure on a frame by shutter and then winding the film by that one frame at a time. In addition, the electric motor rewinds the entire film after completion of photography to store the film in a cartridge. In such electrically powered cameras, an effective way of recording the photographic information in the magnetic tracks is a method for recording information at the time of rewinding the entire film into the cartridge after completion of photography (batch recording method). Specifically, the photographic information for the all frames determined upon exposure is stored once, and when rewinding is carried out later on, the magnetic head is urged against the film surface to record the photographic information en bloc in the magnetic tracks of respective frames passing in succession.
However, with the batch recording method for recording the photographic information for the all frames upon rewinding of the film, when the method described in the above-stated bulletin of Japanese Patent Application Laid-Open No. 6-332065 is applied, the recording frequency of photographic information onto the magnetic track for the final frame cannot be determined. Specifically, in winding the final frame and thereafter rewinding it, the final frame is the recording target frame and there exists no frame located one frame next to this recording target frame when the film is moved in the winding direction. Therefore, the time difference cannot be measured between passage start timings of two perforations, so that a recording time per unit bit of photographic information onto the magnetic track for the final frame cannot be determined.